Artificial nanozymes exerting enzyme functionality are recognized as promising alternatives of natural enzymes in biomimetic chemistry. Natural haloperoxidases that utilize hydrogen peroxide (H2O2) to catalytically convert halide into strong biocidal hypohalous acid hold great promise for thwarting biofouling, while their practical application remains highly questionable as instability of natural enzymes and inadequate H2O2. Herein a semiconducting nanozyme consisting of chromium single atoms coordinated on carbon nitride (Cr‐SA‐CN) that performs bifunctional roles of nonsacrificial H2O2 photosynthesis and haloperoxidase‐mimicking activity for antibiofouling is constructed. Such nanozyme is capable of generating H2O2 from water and O2 upon visible‐light illumination, and then sustainably self‐supplying H2O2 for haloperoxidase‐mimicking reaction in a sequential manner. This dual‐activity Cr‐SA‐CN overcomes H2O2 dilemma and yields hypobromous acid continuously, inducing remarkable bactericidal capability. When used as an eco‐friendly coating additive, it is successfully demonstrated that Cr‐SA‐CN enables an inert surface against marine biofouling. Thereby, this study not only illustrates an attractive strategy for antibiofouling but also opens an avenue to construct valuable nanoplatform with multifunctionality for future applications.

haloperoxidases. [15,16] This kind of natural enzymes can catalyze the two-electron oxidation of halides to microbicidal hypohalous acids (HOX, X: Cl − , Br − , I − ) or analogous oxidized halide species in the presence of hydrogen peroxide (H 2 O 2 ). [17][18][19] Such natural biofilm inhibition utilizing naturally occurring reagents (halide and H 2 O 2 ) represents a promising and environmentally friendly antibiofilm strategy. Nevertheless, natural enzymes often suffer from intrinsic drawbacks such as highcost, poor operational stability, and recyclability. Artificial nanozymes, one kind of nanomaterials combining nanoscale and enzyme-like catalytic functionalities, exhibit advantages such as low-cost and high durability. [20][21][22][23][24] Interestingly, some nanomaterials (e.g., vanadium pentoxide and ceria) have been explored as haloperoxidase-mimicking nanozymes. [25][26][27][28][29] Although high catalytic activity, the carcinogenicity and mutagenicity of vanadium pentoxide could hinder their large-scale application in marine environment. As a heterogeneous metal oxide nanozyme, mixed-valency nanoceria exhibited significantly enhanced catalytic activity towards haloperoxidase-like reaction in contrast to bulk ceria, [28] highlighting that high surface-to-volume ratio and surface geometric effect could strongly affect the activity of a nanozyme. Nevertheless, the haloperoxidase-like performance of nanoceria is relatively low. From a structural perspective, downsizing ceria to nanocluster scale is of significance for maximizing active component utilization and achieving better haloperoxidase-mimicking performance. Unfortunately, most nanomaterials have large particles owing to the natural tendency of agglomeration.Nanostructured materials involving highly dispersed subnanocluster species on supports have been shown to be crucial for enabling heterogeneous catalysts with high intrinsic activity and unexpected selectivity. [30][31][32][33] Nevertheless, stabilizing goaloriented high-density ultrasmall nanoclusters on solid substrates with uniform size and dispersion has been challenged by the thermodynamic instability of nanocluster, poor interfacial hybrid interaction, as well as chemical synthesis. [34][35][36] Herein we propose a fabrication strategy to fabricate hybrid CeO 2 @ ZrO 2 where high-density ultrasmall ceria clusters (≈0.8 nm) are stabilized on zirconia substrates. This unique feature of heterografting CeO 2 @ZrO 2 nanozyme enabled superior and stable haloperoxidase-mimicking performance in selectively catalyzing the oxidation of bromide with H 2 O 2 to hypobromousThe generation of undesired biofouling in medical and engineering applications results in a reduction in function and durability. Copying functionalities of natural enzymes to combat biofouling by artificial nanomaterials is highly attractive but still challenged by the inferior catalytic activity and specificity principally because of low densities of active sites. Here, an innovate strategy is demonstrated to stabilize high-density ...

Biofouling is a common and expensive problem in medical, food, and maritime industries. Artificial nanozymes as functional mimics of haloperoxidases that boost the formation of cytotoxic hypohalous acids from halides and H2O2 are showing increasing potential as a novel class of ecofriendly antibiofouling materials to combat biofilm formation. A photothermal nanozyme (Mo SA‐N/C) with Mo single atoms as active sites that exhibits haloperoxidase‐mimicking capacity is herein developed. Density functional theory calculations indicate that hydroxyl radical from H2O2 dissociation is the key intermediate for hypobromous acid formation. Upon photoirradiation, Mo SA‐N/C generates heat and accelerates the reaction kinetics substantially. Finally, it is demonstrated that Mo SA‐N/C exerts superior broad‐spectrum antibacterial activity and can be applied as an effective coating additive for inhibiting biofouling in real marine conditions. Taken together, this study opens an avenue for developing biocompatible and photo‐response artificial enzymes for our fight against marine biofouling.

Nature has evolved diverse strategies to battle surface biofouling colonization and thus provides us novel insights into designing and developing advanced nontoxic antibiofouling materials and technologies. Mimicking the defense mechanisms of natural haloperoxidases in marine algae in response to biofilm colonization, here we show that the less active MoS 2 shows efficient haloperoxidasemimicking activity through judicious transition metal engineering. Cobalt-doped MoS 2 (Co−MoS 2 ) displays an excellent haloperoxidase-mimicking performance in catalyzing the Br − oxidation into germicidal HOBr, roughly 2 and 23 times higher than the nickeldoped MoS 2 and pristine MoS 2 , respectively. Accordingly, Co−MoS 2 shows an outstanding antimicrobial effect against drug-resistant bacteria and antibiofouling performance in real field tests in marine environments. The realization of robust haloperoxidase-mimicking activity of MoS 2 via metal engineering may open a new avenue to design highly active transition metal dichalcogenides for antibacterial and antibiofouling applications.

Hydrogen peroxide (H2O2) is a powerful industrial oxidant and potential carbon-neutral liquid energy carrier. Sunlight-driven synthesis of H2O2 from the most earth-abundant O2 and seawater is highly desirable. However, the solar-to-chemical efficiency of H2O2 synthesis in particulate photocatalysis systems is low. Here, we present a cooperative sunlight-driven photothermal-photocatalytic system based on cobalt single-atom supported on sulfur doped graphitic carbon nitride/reduced graphene oxide heterostructure (Co–CN@G) to boost H2O2 photosynthesis from natural seawater. By virtue of the photothermal effect and synergy between Co single atoms and the heterostructure, Co–CN@G enables a solar-to-chemical efficiency of more than 0.7% under simulated sunlight irradiation. Theoretical calculations verify that the single atoms combined with heterostructure significantly promote the charge separation, facilitate O2 absorption and reduce the energy barriers for O2 reduction and water oxidation, eventually boosting H2O2 photoproduction. The single-atom photothermal-photocatalytic materials may provide possibility of large-scale H2O2 production from inexhaustible seawater in a sustainable way.